Median right ascension (green curve, left) and declination (black curve, left) of the proper motion components, and parallax (red curve, right) for the KiDS DR4 QSO sample as a function of the GaiaG magnitude. The coloured areas represent the standard deviation of the mean σ/N, where σ is the standard deviation and N is the number of quasars in each bin. The black horizontal line in the right plot represents the parallax zero-point (equals to −0.029 mas, Lindegren et al. 2018).